The Development Of Detection System Of Sulfitation Intensity Based On STM32F407

The sulfitation neutralization as a major stage of sulfuric acid process in cane sugar mill,its primary task is to clarify the cane juice. Sulfitation intensity is used to indicate the numberof sulfur dioxide which is absorbed in the cane juice clarification. It determines the effect ofthe juice’s clarification. The cost will be increased if it’s too high, the effect of clarificationwill be not good enough if it’s too low. It also affects the level of sulfur in the sugar. Therefore,it’s particularly necessary to detect the sulfitation intensity in real-time. Manual titration as atraditional detection method, which have some defects, such as intermittence and operatingerror. All of these shortcomings will affect the real-time detection and the accuracy ofdetection.In this paper, the excessive iodine react with sulfur dioxide, and take starch as theindicator, detect the excess iodine consistency by spectrophotometry, and then calculate thesulfitation intensity. Based on this detection principle, a continuous on-line detection systemhas been designed. The system takes the STM32F407which based on Cortex-M4coreprocessor as central controller. This measurement system is divided into a reaction controlmodule, a data acquisition module, a microprocessor module, a communication interfacemodule and a human-computer interaction module. The system takes a specific wavelength ofthe laser transmitter as the detection light, and takes a silicon photocell as the photoelectricsensor. The signal acquisition module completes signal photoelctric conversion, amplification,optical isolation. The microprocessor module consists of the STM32F407and its peripheralcircuit, this module achieves the overall control. The ADC conversion module which is in theinternal of the microprocessor and has12-bit precision converts analog signals to digitalsignals. The communication interface module includes the CAN interface, the serial ports andthe USB port. The design of this module enrichs the system’s function and provides thepossibility of the system’s expansion. The human-computer interaction module includes LCD,touch screen and buttons. Through the buttons to realize the function selection. The LCD andtouch screen provide a friendly interface.The measurement system can normally run after the debugging of hardware and software. In order to verify system’s function, the sample testing, the repeated experiments andcomparative experiments have been carried out. Experimental data processed by curve regress,the result of fitting reveals that the sulfitation intensity and absorbance are linear, and thenlinear equation of fitting has been written into the program, and calculated the sulfitationintensity by absorbance. The tests proved that the measurement system has high accuracy andexcellent reproducibility. And it can well meet the requirements of the detection.